Diaphragm-sparing regional anesthesia for arthroscopic shoulder surgery: From interscalene block to goal-directed analgesia: A narrative review

Arthroscopic shoulder surgery remains one of the most challenging areas of regional anesthesia. Unlike many other joints, the shoulder is supplied by a complex and overlapping sensory network, making it difficult to achieve consistent analgesia with selective nerve blockade. For decades, the interscalene brachial plexus block has been considered the benchmark technique because of its reliable and profound analgesic efficacy. However, its benefits come at the cost of frequent phrenic nerve blockade and hemidiaphragmatic dysfunction, a limitation that becomes increasingly important in an aging surgical population with reduced respiratory reserve. At the same time, perioperative goals have evolved. Modern arthroscopic shoulder surgery is no longer focused solely on pain relief; preservation of respiratory function, early mobilization, rapid recovery, and patient-centered outcomes have become equally important. These changing priorities have stimulated growing interest in diaphragm-sparing regional anesthesia techniques that seek to balance analgesic efficacy with physiological preservation. This narrative review explores the anatomical basis of arthroscopic shoulder analgesia, the strengths and limitations of conventional interscalene block, and the expanding body of evidence supporting diaphragm-sparing alternatives. Current literature suggests that techniques such as superior trunk block, costoclavicular block, combined suprascapular and axillary nerve blocks, erector spinae plane block, serratus posterior superior intercostal plane block, and other selective approaches may substantially reduce respiratory impairment while providing clinically meaningful analgesia. Although none has completely replaced the interscalene block, the direction of contemporary evidence increasingly favors individualized block selection based on patient characteristics, respiratory risk, and surgical requirements. Rather than replacing a single gold standard, diaphragm-sparing strategies are redefining shoulder regional anesthesia within a goal-directed and patient-centered framework.